Tilt hood assist spring

ABSTRACT

A spring mounted to assist in the movement of a tilt hood for a motor vehicle. The spring is attached to a vertical, relatively fixed element at a point vertically spaced above the pivot point of the tilt hood and applies a constant upward force on the tilt hood. The spring thus lifts the weight off the pivot pin and further is located such that it will assist in movement of the hood from both the fully closed and the fully open position.

United States Patent [191 Stephens et al.

[ Aug. 28, 1973 TILT HOOD ASSIST SPRING [75] Inventors: Donald L.Stephens, Los Gatos;

Roger Paul Penzottl, Fremont, be of Calif.

[73] Assignee: Pacific Car and Foundry Company,

Bellevue, Wash.

[22] Filed: Oct. 28, 1971 [21] Appl. No.: 193,500

[52] US. Cl. 180/69 C, 296/57 A [51] Int. Cl 862d 25/10 [58] Field 0!Search 180/69 R, 69 C, 89; 296/57 A [5 6] References Cited UNITED STATESPATENTS 3,174,575 3/1965 May et al. 180/69 C 3,157,240 11/1964 Chew3,232,368 2/l966 Sullivan 180/69 C 3,556,240 l/197l Hartman l80/69FOREIGN PATENTS OR APPLICATIONS 4/1964 Canada ISO/69C PrimaryExaminer-Leo Friaglia Assistant Examiner-David M. MitchellAttorney-Richard W. Seed, Carl G. Dowrey and Robert A. Jensen et al.

6 Claims, 3 Drawlng Flgurel Patented Aug. 28, 1973 TILT noon ASSISTSPRING BACKGROUND OF THE INVENTION In motor vehicles, and particularlyin the case of large trucks, the access to the engine is extremelyimportant in order to provide rapid and easy servicing of the vehicle.The rapidity of the service is extremely important in order to keep thevehicle, which is a large investment, in running, revenue-generatingservice as large a percentage of time as possible.

In order to provide the access required it is necessary to have theengine covering members such as the hood be an extremely large unit oralternatively be sectional such that when service is necessary theentire engine will be exposed. Normally the engine covering or hood of atruck will include not only what is normally termed the hood but alsothe fenders and related supporting and reinforcing structure all formingpart of a pivotable unit. It is thus apparent that the structure to bemoved to open the engine cavity is a fairly large structural unit andthus embodies a fair amount of weight. In addition to the size and theinherent weight of the structure which must be moved, the height of thetruck above the ground as well as the relative placement of the centerof gravity of the hood assembly make it extremely awkward for anindividual to apply a great deal of leverage to the hood to open orclose the enine compartment.

It has been known in the past to provide assist mechanisms such ashydraulic cylinders or the like to ease the burden of opening andclosing the hoods but these devices are undesirable in that they areexpensive and relatively complex and thus subject to breakdown.

With the above noted problems and prior art in mind it is an object ofthe. present invention to provide an assist spring for a tilt hood truckwherein the spring provides a constant upward pressure relieving thehinge pin of any unnecessary strain and assists in the opening andclosing of the hood with a simple mechanism.

It is another object of the present invention to pro vide a tilt hoodassembly whereina spring is usedto as-. sist in pivoting the tilt hoodabout its pivot point and a cable is provided which prevents the hoodfrom going beyond the desired position. 1 s

BRIEF DESCRIPTION OF THE DRAWINGS.

DETAILED DESCRIPTION OF THE DRAWINGS As can be seen in FIG. 1, a typicaltruck includes a cab which contains the operating mechanism as well asthe seat and steering wheel for the driver. The main frame 4 extendsbeneath the cab and supports an axle upon which the wheels 6 aremounted. At the forward end of the frame there is a bumper 8 and a pivotpin 10 (see FIG. 2) for the tilt hood 12. As shown, the typical tilttype hood for a truck includes the engine covering section 14 as well asthe fenders l6 and their supporting framework 17. mounted to the frameand adapted to be covered by the hood [4 and thus protected from theweather or vandalism is an engine 18 and a radiator 20.

The inventive assist springs, denoted as 22, are secured to the upperportion of the radiator 20 which is a vertical stable member and to alower portion of the fender assembly. Referring now to FIG. 2 it can beseen that the springs 22 are mounted by any acceptable means such asbolts or pins 24 to a rigid framing element 26 upon the radiator 20. Thesprings 22 extend downwardly when in the closed position and slightlyrearwardly to pins 28 secured to one of the frame members 17 within thefender assembly. When the hood is in the closed position, the spring isunder a slight tension, providing lift to the hood for ease in opening.Mounted slightly aft of the springs 22 are control cables 30 similarlymounted to the upper portion of the radiator by means of pins or bolts32 and mounted slightly rearwardly of the spring into the fenderframework 17 by pins or bolts at the point 34.

When the enginge of the truck needs servicing the hood is pivoted aboutpoint 10 and the relative position of points 28 and 34 change but sincethe spring and the cable do not lie in the same vertical plane but liein approximately parallel, vertical planes the cables 30 pass thesprings 22 without any interference.

As shown in phantom, the hood is depicted in an open position, at whichpoint the springs 22 again provide upward lift to assist the operatorwhen it comes time to again close the engine compartment. The cables 30in this position likewise prevent further forward movement of the hoodpreventing damage thereto.

Referring to FIG. 3 and the laws'of basic physics and trigonometry itwill be remembered that if F force applied C the distance from the pointto the applied force,

T,'the torque about a point FXC further by the sine law, for FIG. 3

Sin (b/A Sin OIL T= WR Sin 0 where W= weight of the body R distance frompivot point to center of gravity body 0 angle from the arm to a verticalreference line Hence, the torque developed by the spring (FC=KAB Sin 0)can be made to exactly equal at all tip angles the gravity torqueunbalance (T=WR Sin 0) of a pivoted body. To provide for necessaryunbalance to allow the hood to remain open or closed in the presence ofsmall disturbances like wind or with errors of construction,

the spring force in practice is usually made less than the gravityunbalance.

It can thus be seen by a simple efficient mechanism the hood is capableof providing proper coverage and protection for the engine and yet issimply moved from an open to a closed position or vice versa. The springmembers are constantly under tension providing an upward lift on thehood at all times taking the weight and inherent friction from the hingepin thus again assisting in the movement of the hood. With properadjustment of the length and strength of the spring and proper locationwithin the wheel well of the fender it is possible that the hood couldbe made completely counterbalancing enabling the placement and retentionof the hood assembly in any desired position.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

l. A combination of a tilt hood and assist spring for a truck includinga supporting framework comprising:

an engine covering hood pivotally mounted at its front lower portion toa relatively fixed portion of the truck framework,

means adapted to be covered by said hood extending rigidly upwardly fromthe framework to a position substantially above the lowest portion ofsaid hood when in either its open or its closed position, spring meansattached to the hood and to the upstanding means, the point ofattachment at the hood in the closed position being below the point ofattachment to the upstading means and rearward of the pivotal mountingsuch that the spring means is under continual tension, serving as acounterbalance for the weight of the hood during movement of the hoodfrom one position to another and further removing stress upon the pivotmounting.

2. The combination of claim 1 wherein the upwardly extending member isthe truck radiator. upstanding 3. The combination of claim 1 and furtherincluding a cable member independent of said spring means, having itsends attached in close proximity to the ends of the spring means andlimiting the amount of extension of the spring means.

4. The combination of claim 1 wherein there is a spring means on eachside of the hood.

5. A combination of claim 1 wherein the hood comprises a unit whichcovers the engine and wheels forming a fender wall and the attachmentto.he hood is at the interior of the fender wall.

6. The combination of claim 3 wherein the spring means and cable memberare located such that they move from an approximately parallel relativeposition when the hood is closed to a non-interfering crossed positionwhen the hood is open.

1. A combination of a tilt hood and assist spring for a truck includinga supporting framework comprising: an engine covering hood pivotallymounted at its front lower portion to a relatively fixed portion of thetruck framework, means adapted to be covered by said hood extendingrigidly upwardly from the framework to a position substantially abovethe lowest portion of said hood when in either its open or its closedposition, spring means attached to the hood and to the upstanding means,the point of attachment at the hood in the closed position being belowthe point of attachment to the upstading means and rearward of thepivotal mounting such that the spring means is under continual tension,serving as a counterbalance for the weight of the hood during movementof the hood from one position to another and further removing stressupon the pivot mounting.
 2. The combination of claim 1 wherein theupwardly extending member is the truck radiator. upstanding
 3. Thecombination of claim 1 and further including a cable member independentof said spring means, having its ends attached in close proximity to theends of the spring means and limiting the amount of extension of thespring means.
 4. The combination of claim 1 wherein there is a springmeans on each side of the hood.
 5. A combination of claim 1 wherein thehood comprises a unit which covers the engine and wheels forming afender wall and the attachment to.he hood is at the interior of thefender wall.
 6. The combination of claim 3 wherein the spring means andcable member are located such that they move from an approximatelyparallel relative position when the hood is closed to a non-interferingcrossed position when the hood is open.